diff --git a/aleksis/apps/chronos/frontend/components/AmendLesson.vue b/aleksis/apps/chronos/frontend/components/AmendLesson.vue
index 2d9f8b4c9d2798ba0afcedeb4711debbfa1ae0fc..9dc8a8ff00d3bf8942707075682d4434e2e9a967 100644
--- a/aleksis/apps/chronos/frontend/components/AmendLesson.vue
+++ b/aleksis/apps/chronos/frontend/components/AmendLesson.vue
@@ -159,10 +159,13 @@ export default {
         amends: this.selectedEvent.meta.id,
         datetimeStart: this.selectedEvent.startDateTime.toUTC().toISO(),
         datetimeEnd: this.selectedEvent.endDateTime.toUTC().toISO(),
+        // Normalize cancelled, v-checkbox returns null & does not
+        // honor false-value.
+        cancelled: item.cancelled ? true : false,
       };
     },
     transformPatchData(item) {
-      let { id, __typename, cancelled, ...patchItem } = item;
+      let { __typename, cancelled, ...patchItem } = item;
       return {
         ...patchItem,
         // Normalize cancelled, v-checkbox returns null & does not
diff --git a/aleksis/apps/chronos/schema/__init__.py b/aleksis/apps/chronos/schema/__init__.py
index c6f1cdf0a402ab4eeddd35c372fe41104fc445fd..253f56f183a9391bebf1cc2c4b1322864a4de48b 100644
--- a/aleksis/apps/chronos/schema/__init__.py
+++ b/aleksis/apps/chronos/schema/__init__.py
@@ -107,7 +107,7 @@ class AmendLessonBatchPatchMutation(DatetimeTimezoneMixin, DjangoBatchPatchMutat
     class Meta:
         model = LessonEvent
         permissions = ("chronos.edit_substitution_rule",)
-        only_fields = ("subject", "teachers", "groups", "rooms", "cancelled", "comment")
+        only_fields = ("id", "subject", "teachers", "groups", "rooms", "cancelled", "comment")
 
     @classmethod
     def before_save(cls, root, info, input, updated_objects):  # noqa: A002